Provent's MicroValve acts as a one-way resistor, permitting nearly unobstructed inspiration. During expiration, airflow is directed through small air channels, increasing resistance. This increased resistance during expiration creates nasal Expiratory Positive Airway Pressure (EPAP) which is maintained until the start of the next inspiration. As a result, the device helps pressurize and stabilize the upper airway during the critical end-expiratory period, when the airway has been found to be most narrow in the breaths prior to an apnea.